The present invention relates to a method of manufacturing a carbon nanotube, more specifically, a method of manufacturing a carbon nanotube which can control the chirality.
Carbon nanotube is a material of a graphen sheet of six-membered rings of carbon atoms formed in a tube of a diameter of below several nanometers. The carbon nanotube has good properties, as of high electric conductivity, thermal conductivity, electron emission characteristics, slidability, strength, chemical stability, etc., and their applicability in various fields is being investigated.
It is known that the carbon nanotube has the electric characteristics varied, depending on windings of the graphen sheet, i.e., diameter and chirality of the carbon nanotube to thereby exhibit metal properties or semiconductor properties. Accordingly, to obtain electric characteristics corresponding to applications, it is important to control the diameter and chirality of the carbon nanotube.
The related arts are disclosed in, e.g., Reference 1 (Japanese published unexamined patent application No. 2003-095626), Reference 2 (Japanese published unexamined patent application No. 2003-292313) and Reference 3 (Japanese published unexamined patent application No. 2004-210608).
However, no successful example of controlling the chirality of the carbon nanotube has been found. Yet, successful examples of judging whether the carbon nanotube is metallic or semiconductive are found. In these examples, d.c. voltage is applied to a carbon nanotube which has not been judged metallic or semiconductive. When the carbon nanotube is metallic, large current flows, and the tube is broken. On the other hand, when the carbon is semiconductive, less current flows, and the tube remains unbroken. However, this method cannot select the metallic carbon nanotube alone and cannot control the chirality.
As described above, the method for controlling the chirality, which is very important in terms of the application, has not been yet established, and the metallic carbon nanotube and the semiconductive carbon nanotube so far have not been able to be selectively formed.
Accordingly, for example, in forming a device with semiconductive carbon nanotubes, metallic nanotubes inevitably get into the device structure. For example, in a transistor having the channel of a carbon nanotube, the carbon nanotube which is metallic short-circuits the source and drain, and the amplification and switching operation are not good. In optical devices, the yields of light emission and light detection have been degraded.